Linking Dimensions + a constant

Is there any possible way to make dimensions linked, but with one of the dimensions always a constant amount higher than the other.

For example If i am making a part representing the letter "T", and I always want the vertical line to be 45mm longer than the horizontal so when i change the length of the horizontal line the length of the vertical line automatically updates.

I imagined using linked values might work but I can't seem to be able to add the constant that I want.

any ideas?